Most presidential-primary debates are like a talking doll: Pull the string, and you get the same six sound bites, over and over. But voters may actually get to see signs of human brain activity from the 2012 GOP field in Monday’s Palmetto Freedom Forum in South Carolina.

The forum will consist of three panelists engaging in deep Q&A with the candidates, one at a time. Participants (all those above 5 percent in the polls) will include Mitt Romney, Rick Perry, Michele Bachmann, Ron Paul, Newt Gingrich and Herman Cain.

Designed as a “thinking man’s” twist on the standard debate, the event is meant to reveal what political philosophies (if any) will animate the candidates’ policies and leadership styles.

After all, they’re looking to run against President Obama, who has a coherent, if damaging, governing vision, rooted in the flawed ideas of the Progressives and the Great Society.”

How many of the candidates really understand how Obama has tried to permanently recast the relationship between Americans and their government? Can any offer a more compelling philosophy of his or her own?

Luckily, they don’t have to invent a new one — just return to the eminently sound one articulated in the Constitution. The challenge, of course, is how to apply those constitutional principles in specific ways that can plausibly succeed in today’s America.

Straddling that divide is where the heavy thought lift comes in — and where Monday’s forum, sponsored by the American Principles Project, will be so valuable. Any 2012 aspirant should be able to answer questions like:

* Today, two-thirds of the federal budget goes for payments to individuals, and millions of Americans rely on the government from cradle to grave. How do we get from there to the spirit of limited government the Founders intended?

* Given the founders’ reticence about “overgrown military establishments” and our own budget problems — but also the demands of national security in today’s dangerous world — what should be America’s role abroad?

* After decades of aggressive legislation and court decisions, the careful constitutional balance struck between state and federal governments has been heavily tipped toward Washington. Should we revive federalism? Can we? If so, how?

* The Founders based their system on an informed, participatory, self-reliant citizenry. Is part of the problem that Americans today are falling down on the job? What would you do to get them back on track?

Princeton prof Robert George is a founder of the American Principles Project, which is sponsoring the forum; with South Carolina Sen. Jim DeMint and Iowa Rep. Steve King, he’ll be one of the three panelists asking the questions. He promises no “gotcha questions” or “triviality,” adding that “the minute a candidate begins a stump speech, we’ll cut them off and force the candidate to drill down to really important issues of principle.”

Who benefits most from such a discussion? It could be Romney, who needs to prove to conservatives that he has some core convictions, and that his policies aren’t designed only to check off whatever boxes he needs to win the nomination.

It could be Tea Party favorite Bachmann, who needs to show she can do more than pay lip service to the Founders and propose relevant policies to put constitutional principles into practice.

Or it could be Perry, who needs to shake the perception that he is the lightweight “Gov. Goodhair.” Pollster Scott Rasmussen adds that Perry has the most to lose in any debate, as “he’s coming in as the front runner … [with] some pretty big expectations.”

Those with the most to gain, though, are American voters — put into a bind by a terrible governing philosophy, and deserving of a president who can articulate, and govern by, a better one.